I have a 93 Dodge 1 ton 5.9 diesel. I have an ongoing problem with it jumping in and out of overdrive. It seems to be more prevalent when its raining and/or bumpy conditions. Sometimes it goes for months with no problem. Just returned from a 200 mile trip where it did it for the major portion of the trip.

Have discovered that it loses its ground to the overdrive solenoid. Have installed a switch to give it ground. This always makes it work but does not cure the problem.

Would appreciate any info and suggestion you may have that would alleviate the problem. Its annoying. Has anyone else ever encountered the same thing and if so what was done to correct the problem.

 

I think you hit the nail on the head:
I also think it just goes back to POTS...plain old fashioned troubleshooting....Check ground straps & wires: trans to motor, trans to chassis, grounds through the wire harness.

Don't just give them a visual inspection: Remove ground bolts, looking for corrosion, broken braids, check wire resistance, etc.

HTH; let us know what you find!

Tony

 

You need to see what the tps voltage is at idle. I'm betting it's way too low and needs adjusted or replaced.